1. Field of the Invention
The present invention relates to address management of apparatuses connectable to networks.
2. Description of the Related Art
With the recent widespread use of broadband networks, the use of consumer access lines, such as ADSL (Asymmetric Digital Subscriber Line) and FTTH (Fiber To The Home), has increased. In addition, wireless infrastructures that allow network communication to be performed inside and outside buildings utilizing access points or PHS (Personal Handyphone System) have been established. Furthermore, digital cameras capable of sending captured images to personal computers or the like located at a remote place utilizing these infrastructures have been also suggested.
On the other hand, to carry out communication via IP (Internet Protocol) networks, acquisition of information, such as IP addresses and configuration information, is required. A DHCP (Dynamic Host Configuration Protocol) function has been developed as one of such acquisition mechanisms. This function is realized by DHCP clients and a DHCP server working in cooperation with each other. More specifically, IP addresses to be assigned to the DHCP clients as well as IP addresses of various servers, such as a default gateway and a DNS (Domain Name System) server that allow communication to be performed via the IP networks, are previously set in the DHCP server. By acquiring such information from the DHCP server at the time of booting of the system, the DHCP clients can automatically perform setting of the network information without troubling users.
Furthermore, mobile terminal devices (e.g., a mobile phone, a PHS, a personal computer, a PDA (Personal Digital Assistant), and a digital camera) can stop supplying the electric power to a block having a function for connecting the devices to an IP network when a communication mode is terminated. Since the electric power is not supplied to the block related to communication while the devices are not connected to the network, excessive power consumption is eliminated, as a result of which, saving of the power consumption can be realized.
These devices require processing for acquiring IP addresses or the like every time the devices re-initiate communication and re-connect to the IP network. Accordingly, processing for acquiring information necessary for network setting using the DHCP function undesirably takes time. In addition, when one DHCP server manages many DHCP clients connected to a network, the traffic from and to the DHCP server undesirably increases.
Accordingly, as disclosed in Japanese Patent Laid-Open No. 2005-86263, a technique for establishing a connection to an IP network at the time of the first communication setting and for performing communication thereafter using the initially set information is known. This technique can suppress the traffic to the DHCP server to some extent.
However, digital cameras disclosed in Japanese Patent Laid-Open No. 2005-86263 determine whether the setting information acquired at the time of first communication setting is usable when the digital cameras perform communication setting using the DHCP function thereafter. Accordingly, the digital cameras have to re-acquire setting information if the attempt to communicate with external apparatuses using the setting information acquired at the time of the first communication setting fails. For this reason, the processing for acquiring information necessary for network setting using the DHCP function undesirably takes time.